Her gleefully controversial debut novel concerns a 21-stone woman who joins a violent fightback against anti-fat attitudes. Sarai Walker talks about taking on the liberal werewolves – and why it’s time we stripped fat of its negative connotations

I set up a spoof website to joke about the frustrating way we deal with diversity. The response – applicants seriously trying to hire a minority to keep up corporate appearances - proves that we need more than a punchline